Amino-containing materials such as amino-containing analytes, amino acids, DNA, RNA, proteins, cells, tissue, organelles, immunoglobins, or fragments thereof immobilized on a surface of a substrate can be used in numerous applications. For example, immobilized biological amino-containing materials can be used for the medical diagnosis of a disease or genetic defect, for biological separations, or for detection of various biomolecules. Immobilization of the amino-containing material is typically accomplished by reaction of the amino group with a reactive functional group that is covalently attached to the surface of the substrate.
Substrates having amino-reactive functional groups can be prepared by coating a substrate with a solution of a polymeric material that contains amino-reactive functional groups. Alternatively, substrates having amino-reactive functional groups can be prepared by coating a substrate with a solution of monomers that contain amine reactive functional groups followed by polymerization of the monomers. Exemplary amino-reactive monomers include, for example, N-[(meth)acryloxy]succinimide and vinyl azlactone. An amino-containing material can react with the N-acyloxysuccinimide group resulting in displacement of N-hydroxysuccinimide and formation of a carboxamide. An amino-containing material can react with the cyclic azlactone resulting in an opening of the ring structure.
Although polymeric surfaces that include a reactive functional group such as an N-acyloxysuccinimide group or an azlactone group can react readily with primary or secondary amino-containing materials, such reactive functional groups can suffer from a number of disadvantages. For example, many of the reactions with biological amino-containing materials are conducted in dilute aqueous solutions. Under these conditions, the N-acyloxysuccinimide functional group is known to undergo rapid hydrolysis. This competing reaction can cause incomplete or inefficient immobilization of the amino-containing materials on the substrate.
While azlactone functional groups are more stable to hydrolysis, it is difficult to synthesize an azlactone linked to any polymerizable group other than a vinyl group. The resulting polymeric material has amino-reactive functional groups directly attached to the polymer backbone. In some applications, this can make it difficult for the amino-containing material to get close enough to the amine reactive group for efficient immobilization.